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A note on M. Soares’ bounds

Eduardo Esteves, Israel Vainsencher (2006)

Annales de l’institut Fourier

We give an intersection theoretic proof of M. Soares’ bounds for the Poincaré-Hopf index of an isolated singularity of a foliation of ℂℙ n .

A note on Markov operators and transition systems

Bartosz Frej (2002)

Colloquium Mathematicae

On a compact metric space X one defines a transition system to be a lower semicontinuous map X 2 X . It is known that every Markov operator on C(X) induces a transition system on X and that commuting of Markov operators implies commuting of the induced transition systems. We show that even in finite spaces a pair of commuting transition systems may not be induced by commuting Markov operators. The existence of trajectories for a pair of transition systems or Markov operators is also investigated.

A note on strange nonchaotic attractors

Gerhard Keller (1996)

Fundamenta Mathematicae

For a class of quasiperiodically forced time-discrete dynamical systems of two variables (θ,x) ∈ T 1 × + with nonpositive Lyapunov exponents we prove the existence of an attractor Γ̅ with the following properties:  1. Γ̅ is the closure of the graph of a function x = ϕ(θ). It attracts Lebesgue-a.e. starting point in T 1 × + . The set θ:ϕ(θ) ≠ 0 is meager but has full 1-dimensional Lebesgue measure.  2. The omega-limit of Lebesgue-a.e point in T 1 × + is Γ ̅ , but for a residual set of points in T 1 × + the omega limit is the...

A note on the entropy of a doubly stochastic operator

Brunon Kamiński, José de Sam Lazaro (2000)

Colloquium Mathematicae

We investigate the properties of the entropy and conditional entropy of measurable partitions of unity in the space of essentially bounded functions defined on a Lebesgue probability space.

A note on the fundamental matrix of variational equations in 3

Ladislav Adamec (2003)

Mathematica Bohemica

The paper is devoted to the question whether some kind of additional information makes it possible to determine the fundamental matrix of variational equations in 3 . An application concerning computation of a derivative of a scalar Poincaré mapping is given.

A note on the structure of quadratic Julia sets

Karsten Keller (1997)

Commentationes Mathematicae Universitatis Carolinae

In a series of papers, Bandt and the author have given a symbolic and topological description of locally connected quadratic Julia sets by use of special closed equivalence relations on the circle called Julia equivalences. These equivalence relations reflect the landing behaviour of external rays in the case of local connectivity, and do not apply completely if a Julia set is connected but fails to be locally connected. However, rational external rays land also in the general case. The present...

A note on γ-radonifying and summing operators

Zdzisław Brzeźniak, Hongwei Long (2015)

Banach Center Publications

In this note, we discuss certain generalizations of γ-radonifying operators and their applications to the regularity for linear stochastic evolution equations on some special Banach spaces. Furthermore, we also consider a more general class of operators, namely the so-called summing operators and discuss the application to the compactness of the heat semi-group between weighted L p -spaces.

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